The present invention relates to a capsule for preparing a beverage containing extractable beverage ingredients such as coffee in a beverage production machine.
Single-use beverage capsules are very popular because they provide a fresh tasting beverage quickly, conveniently and in a clean fashion. Therefore, certain beverage capsule systems propose to extract a coffee liquid from roast and ground coffee ingredients contained in a capsule that opens under pressure when a sufficient amount of water has filled the capsule. More particularly, the pressure of liquid increases in the capsule before the delivery face of the capsule opens thereby conferring a good quality of extraction.
In order to provide a thorough interaction between the beverage extractable ingredients, e.g., ground coffee and hot water, it is desirable to delay the release of the beverage through the delivery side. Many different solutions already exist.
In particular, the NESPRESSO® capsule system, as described in EP0512470B1, is based on the principle that an extraction face of the capsule is torn against relief and recessed elements of a capsule holder in the beverage production machine. The extraction face tears at the location of these relief elements and/or recessed elements on reaching the breaking stress to enable the liquid, e.g., coffee extract, to be removed after extraction of the coffee under a certain positive pressure. EP0512468B1 also describes a capsule which is adapted for such extraction process and device.
It exists other methods for providing one or more orifices in the delivery wall due to the internal pressure of the injected liquid, such as involving no (external) perforating elements foreign to the capsule.
It also exists capsules comprising a delivery wall with prefabricated orifices, i.e., which is not opened under the effect of the liquid under pressure in the capsule. However, most of the time, the orifices are configured in their positioning, number and size in the delivery wall to generate a negligible back-pressure causing only a low pressure rise in the capsule. As a result, a relatively poorly extracted and soapy liquid, e.g., “clear” coffee, is produced in the capsule and delivered from it. Thus, improvements over these devices are needed.